Circuit means and apparatus for controlling the air-fuel ratio supplied to a combustion engine

Abstract

A carbureting type fuel metering apparatus has an induction passage into which fuel is fed by several fuel metering systems among which are a main fuel metering system and an idle fuel metering system, as generally known in the art; electrical circuit means responsive to signals produced by associated engine exhaust gas analyzing means, sensitive to selected constituents of such exhaust gas and also responsive to other selected indicia of vehicle and/or engine operating conditions, creates feedback signal means which through associated transducer means become effective for controllably modulating the metering characteristics of the main fuel metering system and the idle fuel metering system.

I claim: 
     
       1. A carburetor for a combustion engine, comprising induction passage means for supplying motive fluid to said engine, a source of fuel, main fuel metering system means communicating generally between said source of fuel and said induction passage means, idle fuel metering system means communicating generally between said source of fuel and said induction passage means, selectively controlled modulating valving means effective to controllably alter the rate of metered fuel flow through each of said main fuel metering system means and said idle fuel metering system means, and electrical circuit means effective for sensing the oxygen content within the exhaust gases of said engine and in response thereto controlling said valving means, said electrical circuit means comprising oxygen sensor means effective for sensing the relative amount of said oxygen in said exhaust gases and producing in response thereto an electrical output signal, means for comparing said output signal to a preselected reference value, amplifier means for amplifying any difference as between said preselected value and said output signal and for producing an electrical control signal effective for controlling said modulating valving means. 
     
     
       2. A carburetor according to claim 1 wherein said modulating valving means comprises solenoid means. 
     
     
       3. A carburetor according to claim 1 wherein said modulating valving means comprises pressure responsive motor means. 
     
     
       4. A carburetor according to claim 1 wherein said modulating valving means comprises first and second valve means, wherein said idle fuel metering system means comprises idle air bleed means, wherein said first valve means is effective to vary the effective flow area of said idle air bleed means in order to thereby alter said rate of metered fuel flow through said idle fuel metering system means, wherein said main fuel metering means comprises metering restriction means, and wherein said second valve means is effective to vary the effective flow area of said metering restriction means to thereby alter said rate of metered fuel flow through said main fuel metering system means. 
     
     
       5. A carburetor according to claim 4 wherein said main fuel metering system means comprises first and second passage means communicating with said source of fuel, wherein said metering restriction means comprises first and second flow restrictor means, wherein said first and second flow restrictor means are respectively situated in said first and second passage means, wherein said second valve means is effective to vary the effective flow area of said second flow restrictor means, and wherein said second passage means communicates generally with first passage means at a point downstream of said first restrictor means. 
     
     
       6. A carburetor according to claim 4 wherein said idle air bleed means comprises first and second air bleed orifices, and wherein said first valve means is effective for varying the effective flow area of said first air bleed orifice. 
     
     
       7. A carburetor according to claim 4 wherein at least one of said first and second valve means is pressure responsive. 
     
     
       8. A carburetor according to claim 4 wherein said first and second valve means are each pressure responsive. 
     
     
       9. A carburetor according to claim 4 wherein said idle air bleed means comprises first and second air bleed orifices, wherein said first valve means is effective for varying the effective flow area of said first air bleed orifice, wherein said main fuel metering system means comprises first and second passage means communicating with said source of fuel, wherein said metering restriction means comprises first and second flow restrictor means, wherein said first and second flow restrictor means are respectively situated in said first and second passage means, wherein said second valve means is effective to vary the effective flow area of said second flow restrictor means, and wherein said second passage means communicates generally with said first passage means at a point downstream of said first restrictor means. 
     
     
       10. A carburetor according to claim 9 wherein said first and second valve means are pressure responsive. 
     
     
       11. A carburetor according to claim 1 and further comprising venturi means carried in said induction passage means, wherein said main fuel metering system means comprises main fuel discharge nozzle means situated generally in the throat of said venturi means, and further comprising variably positionable throttle valve means situated in said induction passage means, idle fuel discharge aperture means formed in a wall of said induction passage means and situated as to be generally juxtaposed to a portion of said throttle valve means. 
     
     
       12. A carburetor according to claim 11 wherein said main fuel metering system means further comprises a main fuel well, a first flow restrictor communicating between said source of fuel and said main fuel well, a second flow restrictor communicating between said main fuel well and said source of fuel, said first and second flow restrictors being in generally parallel flow relationship to each other, and wherein said modulating valving means is effective for varying the effective flow area of one of said first and second flow restrictors. 
     
     
       13. A carburetor according to claim 12 wherein said idle fuel metering system means comprises first air bleed orifice means effective for bleeding generally ambient atmospheric air into the fuel flowing through said idle fuel metering system means, and further comprising second air bleed orifice means effective for bleeding generally ambient atmospheric air into said fuel flowing through said idle fuel metering system means, and wherein said modulating valving means is effective for varying the effective flow area of said second air bleed orifice means. 
     
     
       14. A carburetor according to claim 13 wherein said modulating valving means comprises a first variably positionable valve member, a second variably positionable valve member, a first pressure responsive wall member operatively connected to said first valve member, a second pressure responsive wall member operatively connected to said second valve member, said first and second wall members each being adapted to be exposed to a controlled pressure differential as to be thereby urged in respective first directions, and resilient means operatively connected to said first and second valve members to yieldingly resist movement of said first and second valve members in said first direction. 
     
     
       15. A carburetor according to claim 14 wherein said pressure differential is at least in part determined by the magnitude of venturi vacuum generated by air flow through said venturi throat. 
     
     
       16. A carburetor according to claim 14 wherein said pressure differential is at least in part determined by engine vacuum communicated from said engine to said first and second pressure responsive wall members. 
     
     
       17. A carburetor for a combustion engine, comprising induction passage means for supplying motive fluid to said engine, a source of fuel, main fuel metering system means communicating generally between said source of fuel and said induction passage means, idle fuel metering system means communicating generally between said source of fuel and said induction passage means, selectively controlled modulating valving means effective to controllably alter the rate of metered fuel flow through each of said main fuel metering system means and said idle fuel metering system means, and electrical circuit means effective for sensing the oxygen content within the exhaust gases of said engine and in response thereto controlling said valving means, said electrical circuit means comprising oxygen sensor means effective for sensing the relative amount of said oxygen in said exhaust gases and producing in response thereto an electrical output signal, means for comparing said output signal to a preselected reference value, amplifier means for amplifying any difference as between said preselected value and said output signal and for producing an electrical control signal effective for controlling said modulating valving means, said modulating valving means comprising first and second valve means, said idle fuel metering system means comprising idle air bleed means, said first valve means being effective to vary the effective flow area of said idle air bleed means in order to thereby alter said rate of metered fuel flow through said idle fuel metering system means, said main fuel metering means comprising metering restriction means, said second valve means being effective to vary the effective flow area of said metering restriction means to thereby alter said rate of metered fuel flow through said main fuel metering system means, and said first and second valve means comprising first and second linear solenoid valve means. 
     
     
       18. A carburetor according to claim 9 wherein said first and second valve means respectively comprise first and second linear solenoid valve means. 
     
     
       19. A fuel metering system for a combustion engine having engine exhaust conduit means, comprising fuel carbureting means for supplying metered fuel flow to said engine, said carbureting means comprising induction passage means for supplying motive fluid to said engine, a source of fuel, main fuel metering system means communicating generally between said source of fuel and said induction passage means, idle fuel metering system means communicating generally between said source of fuel and said induction passage means, controlled modulating valving means comprising associated solenoid winding means effective to controllably alter the rate of metered fuel flow through each of said main fuel metering system means and said idle fuel metering system means, oxygen sensor means effective for sensing the relative amount of oxygen present in engine exhaust gases flowing through said exhaust conduit means and producing in accordance therewith a first output signal, and logic control means effective for receiving said first output signal and in response thereto causing said modulating means to alter said rate of metered fuel flow, said logic control means comprising first electrical buffer means for buffering said oxygen sensor output signal, amplifier means for receiving an electrical signal from said buffer means and in turn creating a second output signal effective to energize said solenoid winding means in response to and in accordance with said first output signal. 
     
     
       20. A fuel metering system according to claim 19 and further comprising transducer means for sensing engine temperature and producing in response thereto a third output signal, and wherein said logic control means is effective for receiving said third output signal as an input thereto. 
     
     
       21. A fuel metering system according to claim 19 and further comprising variably positionable throttle valve means in said induction passage means, and transducer means for sensing when said throttle valve means is at or near a wide open condition and producing in response thereto a third output signal, and wherein said logic control means is effective for receiving said third output signal as an input thereto. 
     
     
       22. A fuel metering system according to claim 19 and further comprising first transducer means for sensing engine temperature and producing a third output signal in response thereto, throttle valve means situated in said induction passage means, and second transducer means for sensing when said throttle valve means is at or near a wide open condition and producing a fourth output signal in response thereto, and wherein said logic control means is effective for receiving said third and fourth output signals as inputs thereto. 
     
     
       23. A fuel metering system according to claim 19 and further comprising pressure transmitting conduit means effective for transmitting engine developed vacuum to said modulating valving means, and wherein said logic control means comprises pressure control valve means for regulating the magnitude of said engine vacuum applied to said modulating valving means. 
     
     
       24. Electrical circuit means in combination with a carburetor having valving means for controlling the rate of flow of fuel into an associated engine, comprising oxygen sensor means for sensing the relative amount of oxygen present within the exhaust gases of said engine and effective for producing a first electrical output signal of a magnitude reflective of said relative amount, first electrical buffer means effective for receiving said first output signal and in response thereto creating a second output signal of related magnitude, means for establishing a preselected reference magnitude, electrical amplifier means effective to receive said second output signal and compare said related magnitude to said reference magnitude and produce an amplified third output signal of a magnitude related to the different therebetween, solenoid winding means associated with said valving means for varying the operating position of said valving means, and electrical switching means responsive to the occurrence of said third output signal for energizing said solenoid winding means in relation to the magnitude of said third output signal. 
     
     
       25. Electrical circuit means according to claim 24 wherein said solenoid winding means comprises first and second solenoid coils. 
     
     
       26. Electrical circuit means according to claim 24 wherein said amplifier means comprises first and second operational amplifiers. 
     
     
       27. Electrical circuit means according to claim 24 wherein said amplifier means comprises first and second operational amplifiers, wherein each of said first and second amplifiers receive said second output signal, wherein each of said first and second amplifiers produce said third output signal, wherein said switching means comprises first and second solid state switching means, wherein said first and second switching means respectively respond to said third output signals from said first and second amplifiers, wherein said solenoid winding means comprises first and second solenoid coils, and wherein said first and second switching means are respectively effective for energizing said first and second coils. 
     
     
       28. Electrical circuit means according to claim 24 wherein said switching means comprises transistor means situated generally between a source of electrical potential and said solenoid winding means. 
     
     
       29. Electrical circuit means according to claim 24 wherein said solid state switching means comprises a Darlington circuit. 
     
     
       30. Electrical circuit means according to claim 27 wherein each of said first and second switch means comprise Darlington circuits. 
     
     
       31. Electrical circuit means according to claim 27 wherein said valving means comprises first and second valving members, wherein said first valving member is effective to alter the rate of fuel flow through a first fuel metering system of said device, wherein said second valving member is effective to alter the rate of fuel flow through a second fuel metering system of said device, wherein said first solenoid coil controls said first valving member, and wherein said second solenoid coil controls said second valving member. 
     
     
       32. Electrical circuit means according to claim 24 and further comprising additional means responsive to indicia of engine operating conditions for energization of said solenoid winding means regardless of whether said amplifier produces said amplified third output signal. 
     
     
       33. Electrical circuit means according to claim 32 wherein said additional means comprises additional electrical circuit means controlled in response to the position of a throttle valve of said engine, and wherein said additional circuit means is effective to energize said solenoid winding means to a maximum energization whenever said throttle valve is in a wide open position. 
     
     
       34. An electrical circuit for controlling the energization of first and second solenoid coils in response to an electrical operating signal of variable magnitude, comprising first, second, third, fourth and fifth operational amplifier means, first and second transistor means comprising first Darlington circuit means, third and fourth transistor means comprising second Darlington circuit means, first and second voltage divider means, said first amplifier means being effective to receive said operating signal and to produce a first electrical output signal of a magnitude reflective of the magnitude of said operating signal, first terminal means associated with said second amplifier means and effective for receiving said first electrical output signal, second terminal means associated with said third amplifier means and effective for receiving said first electrical output signal, third terminal means associated with said second amplifier means and effectively connected to said first voltage divider means as to thereby establish a first reference magnitude for said second amplifier means, fourth terminal means associated with said third amplifier means and effectively connected to said second voltage divider means as to thereby establish a second reference magnitude for said second amplifier means, fifth terminal means associated with said second amplifier means for producing a first amplified output signal indicative of the difference in magnitude between said first electrical output signal and said first reference magnitude, sixth terminal means associated with said fourth amplifier means and effective to receive said first amplified output signal, seventh terminal means associated with said fourth amplifier means for producing a second output signal, first base electrode means associated with said first Darlington circuit means for receiving said second output signal and in response thereto causing an output collector-emitter of said first Darlington circuit means to energize said first solenoid coil through first conductor means, eighth terminal means associated with said fourth amplifier means and electrically connected to said first conductor means, ninth terminal means associated with said third amplifier means for producing a second amplified output signal indicative of the difference in magnitudes between said first electrical output signal and said second reference magnitude, tenth terminal means associated with said fifth amplifier means and effective to receive said second amplified output signal, eleventh terminal means associated with said fifth amplifier means for producing a third output signal, second base electrode means associated with said second Darlington circuit means for receiving said third output signal and in response thereto causing an output collector-emitter of said second Darlington to energize said second solenoid coil through second conductor means, and twelfth terminal means associated with said fifth amplifier means and electrically connected to said second conductor means. 
     
     
       35. An electrical circuit according to claim 34 and further comprising third conductor means electrically connected to said second conductor means and to transducer means wherein said transducer means is responsive to input signals requiring overriding of said electrical operating signal. 
     
     
       36. Electrical circuit means according to claim 24 and further comprising oscillator means, said oscillator means being effective electrically interposed between said amplifier means and said switching means and effective to pulsatingly energize said solenoid winding means. 
     
     
       37. Electrical circuit means according to claim 36 wherein said oscillator means comprises resistor means and capacitor means forming an R-C network, and further comprising auxiliary switching means closed in response to the occurrence of selected engine operating conditions, said auxiliary switching means being effective when closed to apply additional voltage to said R-C network to thereby accordingly shorten the charging time of said capacitor means. 
     
     
       38. Electrical circuit means according to claim 37 wherein said auxiliary switching means comprises first and second solid state switching means, and wherein said first and second solid state switching means are closed in response to separate ones of said selected engine operating conditions, and wherein each of said first and second solid state switching means is effective when closed to apply additional voltage to said R-C network to thereby accordingly shorten the charging time of said capacitor means. 
     
     
       39. Electrical circuit means according to claim 38 wherein said electrical switching means comprises Darlington circuit means. 
     
     
       40. Electrical circuit means according to claim 38 wherein said valving means are each fluid pressure actuated, wherein pressure controller valve assembly means are employed for establishing a selectable magnitude of said fluid pressure, and wherein said controller valve assembly means comprises as a portion thereof said solenoid winding means. 
     
     
       41. Electrical circuit means according to claim 38 wherein said first solid state switching means comprises first transistor means, wherein said second solid state switching means comprises second transistor means, and further comprising first transducer means responsive to one of said engine operating conditions for at times making said first transistor conductive, and second transducer means responsive to an other of said engine operating conditions for at times making said second transistor conductive. 
     
     
       42. Electrical circuit means according to claim 41 wherein said first transducer means is responsive to the temperature of said engine, and wherein said second transducer means is responsive to the degree of opening of a throttle valve associated with fuel metering device.